Field of the Invention
The present invention relates to an aqueous solution containing a nonionic surfactant and a hydrotrope containing an alkyl phenoxy polyethoxy phosphate and an alkyl glucoside.
Introduction
A challenge with aqueous cleaning formulations is achieving stability of the formulation in a range of environments and temperatures, desirably while at the same time minimizing foaming. A cleaning formulation often contains one or more nonionic surfactants and may further contain a base such as sodium hydroxide or potassium hydroxide and other electrolytes. Electrolytes decrease the solubility of nonionic surfactants and result in destabilization of the formulation. Likewise, increase temperatures tend to destabilize the formulation by decreasing the solubility of the nonionic surfactants. Often, a hydrotrope is included in the formulation to enhance solubility of the nonionic surfactants and improve formulation stability over temperature and electrolyte concentration ranges of interest.
It is desirable to maximize the efficiency of hydrotropes that are included in cleaning formulations. That is, it is desirable to identify a hydrotrope that maximizes cloud point temperature of an aqueous cleaning formulation containing nonionic surfactant and electrolytes for a given concentration of hydrotrope. The cloud point temperature is the temperature at which one or more than one component of a solution is no longer completely soluble in the solution and reveals at what temperature the solution becomes unstable. Higher cloud point temperatures indicate higher stability.
It is further desirable to minimize foaming of the cleaning formulation in many applications. Processes that require circulation of cleaning formulations are inhibited by foaming, which can cause variation in the rate of formulation circulation and even cause the circulation to shut down. Foaming can also cause overflow in containers holding cleaning formulations.
Therefore, it is desirable to identify a formulation that maximizes cloud point temperature and, desirably, minimizes foaming for an aqueous cleaning solution containing a nonionic surfactant by maximizing the efficiency of a hydrotrope in the formulation.